I think that if the miners left bitcoin and switch to bitcoin cash that will have a huge impact on the bitcoin market but then again, let us not forget that these miners get rewarded because of the transaction that happens or should i say it is the reward for solving complex algorithm. With this being said, just means that in order for the miners to leave bitcoin completely is that the community should not be using bitcoin anymore and have switched to BCH so transactions only happens on BCH and not BTC but this is not going to be the case since BTC is already established and more investors, businesses and entrepreneurs accept bitcoin rather than any alt coins.

Bitcoin normally adjusts the difficulty every 2 weeks. If half the miners leave, those 2 weeks turn into 4 weeks. If 90% of the miners leave, it will be 20 weeks.Bitcoin Cash now has about 30 blocks per hour, instead of the 6 it should mine. It's the ping-ponig result of the emergency difficulty adjustment it has. https://electroncash.org/ says there will be a hard fork on Bitcoin Cash on November 13th, and I assume that will end the emergency difficulty adjustment.I understand why miners LOVE to get 30 blocks per hour, it's easy money. What I don't understand, is why people start buying their Bitcoin Cash for a higher price when they mine more. It must be a pump, and that will most likely end in a Bitcoin Cash crash again.

Meanwhile, Bitcoin fees are higher than ever, $10 isn't enough anymore for the smallest transaction. I'm more and more starting to think the small blocks are actually meant to create FUD, forks and pump&dump actions! Some people must be earning a lot of money from this.

If Bitcoin Core would have increased blocksize long before fees spiked, and long before miners earned millions of dollars per day from fees, all this would never have happened. I now can't even use Bitcoin for online food orders anymore, as the fee would double the price.

Miners are switching to BCH, because right now it is more profitable to mine Bitcoin Cash when compared to Bitcoin. And most of the miners care only about the profits. I would not blame them, as they have to take care of the expenses (such as capital costs, electricity, manpower.etc).

I have heard if the mining pool lowers, the difficulty automatically lowers so less evolved machines can mine to fasten the transactions?

yes, the transaction must be fasten if there has a miners, but if we haven't any bitcoin miners, the transaction must be slower than snail or internet explorer but i think it cannot be happen because the earn a lot of money in bitcoin, so it has a low chance.